Imaging system design using focal plane detector arrays is becoming ubiquitous, and the image formation burden is increasingly shared between the optical train and digital processing of the raw detector array data. Imaging system resolution, focal plane array sampling, and field of view are a function of the imaging sampling parameter Q, where Q=λ*(focal ratio)/(detector element size). The degree of spreading (blurring) of the image of a point source is a measure for the quality of an imaging system. Current practice is frequently to settle for less than the desired imaging performance when the system parameters exceed those attainable by a Q=1 system, and to accept the pixel-limited image sampling resolution of available focal plane detector array imagers.
In a detector element size-limited optical system (Q<1), Mark Neifeld and Amit Ashok successfully increased the system sampling by improving Q by a factor of three (as described in “Pseudorandom Phase Masks for Super-resolution Imaging from Subpixel Shifting”, Applied Optics, May 2007, the contents of which are hereby incorporated by reference.) However, the approach required significant tuning of a nonlinear iterative algorithm to a carefully calibrated phase plate, operations too cumbersome in practice and resource-intensive to have yet found wide application in deployed systems.
Thus, what is needed is a fast (e.g., real-time), single-pass phase-closure method and apparatus that overcomes pixel-limited performance to increase the effective sampling by an optical system to achieve a higher sampling parameter Q.